The present invention relates to liquid crystal displays which are capable of transmitting light in selected portions as controlled by an electronic circuit in which the properties of the transmitted light are selected by the selective interposition of a light modifying device between the light source and the liquid crystal display (hereinafter LCD).
LCD's are known with backlighting arrangements and with filters, such as is shown in U.S. Pat. No. 4,486,077 to Torresdal in which an optional color filter is interposed between a light control block and an LCD mounted on a printed circuit board. However, the filter is merely held in place by being sandwiched between those elements. As such, it may be difficult to replace the filter, or to selectively install a filter during assembly, when desired.
In particular, in the manufacture of fuel dispensers in which elements such as the price per gallon, number of gallons delivered, and transaction price based upon the number of gallons delivered need to be displayed to a purchaser of fuel, it has become known to use such LCD's. It is considered desirable to provide such LCD's illuminated in colors to coordinate with the marketing color scheme of the fuel vendor. Thus, in the manufacture of such fuel dispensers, it is desirable to have such filter elements capable of easy installation as required from an existing inventory of filters into an existing inventory of LCD-equipped dispensers.
Further, in addition to or as an alternative thereto, it is sometimes helpful to provide a reflective surface behind an LCD to improve the visibility thereof in certain daylight conditions. So arranged, the reflective surface captures ambient light rays and reflects them through the LCD to improve the visibility thereof.
Clearly, changing the filter disclosed in the Torresdal patent would require excessive disassembly and initial or subsequent filter installation would take additional time and may result in damage to the LCD. There is need in the art for an LCD filter and/or reflector which can be easily and quickly installed and yet which stays in its installed position despite the vibration involved in transport to an installation site.